Electrical-resistance device.



5.1. OIINGTON.`

GE DEVICE.

APPLICATION FILED APR. 26, 1910.

ELECTRICAL RBSISTAN Patented Feb. 11, 1913.

2 SHEETS--SIEBT l.

@miel E. J. OVINGTON. ELECTRICAL RESISTANCE DEVICE.

APPLIGATION FILED APR'ZG, 1910.

Patented Feb. 11, 1913.

2 SHEETS-SHEET 2,

EDWARD J. OVINGTQN, OF LOS ANGELES, CALIFORNIA, ASSIG-NOB, BY MESNE ASSIGN- MENTS, T0 SIMPLEX ELECTRIC HEATING CGMPANY, 0F CAMBRIDGE, SETTS, A CORPORATION OF MASSACHUSETTS.

y Application filed.- April 26,*:19-10. Serial No. $57,818.

To all 'whom t may concern.'

Be it known that I, EDWARD'J. OVINGTON, a citizen ofthe United States, residing at Los Angeles, in the county of Los Angeles and State of California, have invented a new and useful Electrical-Resistance Device, of which the following is a specification.

This invention relates to an electrical resistance device adapted to rapidly radiate heat generated in the .same by the electrical current and yin its practical. application is adaptedv for various forms of heating devices for various uses. l

One object of the invention'is to provide a resistance device which is especially adapted to become highly heated and to impart its heat to surrounding materials or objects without sustaining injury to itsel'f.

Another object of the invention is to provide a superior immersion electrical heater giving a mechanical and thermal bond between the resistance element and the external shell, and which heater will not be liable to burn out from the heat produced by the current "even though non-immersed while the electricaleurrent is on so that it will not be incapacitated though allowed to remain in a vessel with the current turned on after the liquid has all been evaporated by boiling. A

- A fu-rther object is to produce the most intimate contact between the ,cover or shell and the resistance element by producing ay shrinking "tension within the metal itself, whereby the use of devices extraneous to the cover, for causing the cover to press tightly against the resistance element, is obviatcd, and the means for producing the tension is self-contained within the cover, that is to say, the fiber or grain of lthe metal o-f which the cover or shell is composed is given a sustained strain by spinning it into shape, which results in asustained shrinking tension bringing the inner surface Aof the shell into tight cont-act with the resistance element and excluding the air from between them, thereby attaining a high degree of heat con ductivity from the resistanceelement tothe shell.

` Other objects and advantages will appear from the subjoined specification` and claims.

My invention comprisesv a support, an

electrical resist-ance element disposed-on the support and having an uneven surface, a

Specification of Letters Patent.

i 'ELECTRICAL-RESISTANCE DEVICE.

Patenten Feb, 11,1913.

heat conductin electrical insulating sheet disposed on an conforming to the uneven surface of the resistance element, and an eX :ternal heat vconducting metal shell having I thermal cont-act with the resistance element .disposed about the insulator and conforming -on the face which is in contact with the insulation to said uneven surface.

The invention may be carried' out in various forms and in the accompanying drawings I have shown an embodiment thereof ,which at t-he present I deem most effective.

The accompanying drawings .illustrate the invention in the preferred form. A

' Figure l is a perspective view of an immersion heater constructed in accordance with this invention and. ready for use to heat a glass of water. Fig. 2 is a broken sectional view of the heater shown in Fig. 1. The upper part of the handle is shifted and turned half way around from the body. In Fig. 3, line .912, indicates the plane of lsection of the main body, and line mb, indicates the plane of section of .the upper part of the handle. Fig..3 is an enlarged cross section of the handle on line w3, Fig. 2, looking doWn.- Fig. 4 is an enlarged cross sect-ion on line r4, Fig. 2, looking up. Fig. 5 is an enlarged section on line m5, Figs. 2 and 6, looking up. Fig. 6 is an enlarged fragmental section' on line mae-, Fig. 5. The head and body of the low resistance pieces are intact. Fig. 7 is a magnified sect-ionel detail of fragments of the shell, insulatio.` resistance and core as held together at a point where longitudinal boresl, and is provided near opposite ends with transverse perforations 9. and 3 to receive low resistant conducting A pieces i and 5 which are preferably split pins in the nature of cot-ter pins provided at their outer ends with heads 6 which are embedded in the material of the core, and are practically flush with the exterior of the core that forms Athe support for the resistance element 7 `which is disposed about the eX- terior surfaceof the core and the terminals of which are connected with the conducting pieces 4 and 5 respectively. lVithin the cavity of the core are disposed the. lead wires 8 and 9 whichare surrounded with heat proof insulation 10 and are brought together at one end of the cavity of the core and extend thence from said core.

The resistance element shown, is a cylindrical wire of high resistance material well known in the art, and is wound tightly around the corel in the form of a coil, the convolutions of which are spaced apart. Preferably the core is provided with an external spiral groove 11 in which the resistance coil is seated. Said groove is of less depth than the diameter ofthe wire so that the resistance forms an uneven surface on the outside of the core. Disposed over said core and resistance is a yielding iiexible electrical insulating resistance cover 12 of noncombustible heat conducting material which is preferably thin sheet mica, well known in the art. Said mica is made to conform to the irregularities of the unevenl exterior surface of the resistance. y

Disposed at the ends of the core are two electrical insulating sheets 1P and 14, one of said sheets 14 being` provided with a central perforation 15 througl. which the insulated' leads or conductors 8 and 9 are led. The end of the core opposite that from which the conductors are led is rounded or beveled as indicated at 16, and a concaveconvex sheet metal cap 17 is fitted against the mica sheet 13 and the'ioundedor bevel end of the core is provided with a peripheral gain 18 in which the rim of the concaveconvex sheet metal cap 17 is seated. Said rim is preferably bent to conform to the. gain and thus provide an annular recess 19 to receive a resilient heat-resisting, waterproof packing 20, which may be of gra phited asbestos.

Plain or ungrooved necks 21 and are provided at the ends of the core beyond the perforatons 2 and 3 through which the conducting pieces 4`and 5 extend. An external heat conducting metallic shell casing or envelop 24 is disposed around -the cortand over the perforated mica sheet 14 and is provided with a tubular neck 213 to re ceive a tubular handle 27 which passes through and is bi'azed in the neck 2G and is provided interiorly of the shell with a flaringuend Q8 to lit againstthe inside of the she The method of producing the resistance,

device sho-wn in the drawings is as follows:l The insulating core 1, which in this instance forms a supportfor the resistance element posed.

thereof on which the resistance is to b e dis- Said support may be externally groved by machinery or by a process of molding the groove being spiral to seat a resistance coil formed of a suitable Wire 7. The insulated leads 8 and 9 are insheathed in a braid 29 to forni a conducting cord, well known in the art, and are bundled together with an asbestos packing cord 30 disposed on each side of the sheath. The bundle is then bound together by tape 31 wound thereon thus forming a cable. The asbestos cord is preferably bent to forni a knot around the insulated leads 8 and 9 indicated at 32 inFig. 2. When this has been done the leads are ready for connection with the low resistance conductor pieces.

One terminal of the resistance wirel 7 is applied to the core by inserting the same with a cotter pin 4 from the outside of the core through to the inside of the core, .and the resistance wire is then wound on the core from sueh cotter pin toward the other perforation through which it is passed with another cotter pin and drawn tight. Then washers 33 are passed over the cotterpins and the inwardly extending ends of the resistance Wire, which ends are then wrapped around the pin. Loops are formed on the ends of the leads 8 and'9 and are placed around the inwardly projecting ends of the cotter pins and against the Washers, and the limbs of the cotter pins are then spread apart and bent over the loops, the resistance wire andthe Washers, and are firmly pressed against the saine.l Then the cord .with its tape winding is passed through a tapering collar 34 of heat-resisting and electrical non-conducting material, such as porto bring the collar 34 and the knot of asbestos packing firmly into place and then the core 1 is pressed tightly into the lined shell, care being taken that the conducting pieces 4 and v5 are brought opposite the lap joints of the mica sheets so that a double thickness of mica insulation Will occur between said conducting pieces and the shell. AThen the mica cap 13 is inserted against the end of the core and the metal cap or end piece 17, which is of the same material as the shell and is bent at its edges to conform tothe gain 18, is inserted into the shell and against the core. Then the shell is inserted into Losetas.

thevchuck of a lathe, not shown, the cord and the handle being inserted through the i bore of the chuck and spindle of the lathe,

. `the backl end ofthe lathe spindle.

a ,man

and for convenience disposed in such a Way asfto allow the shell and core to be rotated without entangling the cord. This may be done by rolling the cord into a loose ball and inserting it into a receptacle attached to rlhe workman will then clamp the core and metal shell between the lathe centers and will then proceed with a suitable tool to spin the shell, soas to compress said shell, the mica and the resistance tightly about the core. This method or process results. in conforming the shape of the lnica lining and the inner surface of said metal shell to the outer uneven surface formed by said resistance. and also results in forcing the parts into tight, intimate, interlocking contact, and in increasing the heat-receiving surfacelof the metal shell. The unevenness of surface of the metal shell and the mica lining tends also to hold the resistance and to prevent the same from shifting to any greatextent. Said method also produces a contracting strain which tends to maintain very close thermal contact between the resistance producing the heat, and the metal shell which is to impart the heat.

vAfter the shell has been' spun onto the core, the Workman may, by a, suitable tool, trim the projecting edge of the shell into the beveled form which is seen at 35, and then the -resilient packing l will be inserted into the recessr 19. n

\ At the outset, those parts of the inner surface of the projecting portion of the shell 24 and of the outer surface of the shell cap 17, which is to contact therewith, will be tinned so that when sufficient heat occurs between said contacting surfaces, such surfaces will become soldered together.

When the shell cap 17 and mica 18 have been brought into place as stated, the Workman will then spin the projecting bevel edge of the shell down onto the shell cap, tightly compressing the resilient packing 20, shell cap 17 and the insulated cap 13 tightly against the end ofthe core. As a result: of this operation the concavo-convex cap 17 is v firmly held in convex form externally and the spun shell 24 and the shell cap are sealed together.

The spun metal shell around the necks at the ends of the core at each side of the jresistance element holds 'the mica tightly To complete the device the leads may be provided with an electrical connection 38 for attachment to a fixture 39, the'current is turned on the resistance becomes quickly heated and heat is rapidly transmitted through the portion of the shell adjacent thereto.4 The heat thus evolved by the resistance-raises the temperature of the spun shell body 24 and the shell cap 17 at the tinned lap, (adjacent 35 in Fig. 6) sufficiently to effect the soldering of the joint between the shell and the cap. After the shell and cap have' thus been soldered together, the same, together with the handle are suitably cleaned, polished and otherwise prepared for market in any Well-known manner.

In practical use the convex form ofthe cap 17 enables the device when it rests on a flat surface 40 to be supported by a very small area at that portion of the cap which is farthest from the source of heat and when the immersion heater, shown in Figs. 1 and 2, is left at'rest in the glass or other vessel 41 containing liquid,4 the evolved heat is most effectively applied to raise the temperature of the liquid; andthe tendency to heat the vessel is minimized.

By reason of the convexity of the bottom surface-of the heater, steam or air bubbles which are formed thereon, will pass upward and laterally to the sides of the heater, thus preventing overheating of the bottom of the heater and of the adjacent pnrtions of the water containing vessel.

I claim 1. A resistance device comprising a resistance element, a support therefor projecting beyond the resistance element to form necks, ashell around said resistance and its support andan insulating lining in thc shell and around the support and resistance, said insulating lining being crimped and conforming to the necks and to the uneven surface. formed by the resistance, and the inner surface of thc shell conforming tothe crimped lining and practically conforming to said uneven surface, said shell, insulation, resistance and support being in tight 'thermal coni act.

2. An electrical heater comprising a hollow insulated core havingagencral circular form in cross-section, low resistant electrical conducting pieces extending through the material of the core from the bore to the outside surface of said core, the 'outer ends being Hush with said surface, an electrical resistance disposed on the outside surface of said core and connected at its terminals withI said ccmluctrrs, heat conducting electrical insulation around the core and said resistance, an external heat-conducting shell of metal closely conforming to the outer surface of the resistance element, and in tight thermal contact therewith through the electrical insulation, and means for conducting the terminals connected to the low-resistant electrical conducting pieces through said shell.

3. An electrical immersion heater com. prising an electrical resistance element, conductors attached to said element, electrical insulation around said element, a metallic shell having a cap and inclosing said element and insulation7 a-hollow handle form# ing an exit for the conductors from the shell, and packing of heat-resisting Water proof material to make the joint between the cap and the shell water-proof.

4.. An electrical heater comprising a core, leads extending inside the core, electrical resistance disposed on the exterior of the core, low resist-ant electrical conducting pieces between the leads and the terminals of the resistance, and a shell'surrcunding and electrically insulated from, and in tight thermal. contact with, the resistance and the outer ends of said pieces.

5. An electrical heater comprising a holloW core of a general circular form in crosssection, an electrical resistance disposed around said core, low-resistant electrical conducting pieces, eXtending from the interior to the outside surface of the core, the outside ends of said pieces being flush with such surface, a shell surrounding the resistance and core and in tight thermal contact with the resistance and the outer ends 'of said pieces, and electrical insulation between the shell and said resistance and.

.trical insulating heat-conducting medium on and conforming to said surface, and a shell on said medium and conforming to said surface.

7. An electric heating` device comprising a support, a coil of resistance forming an uneven surface on the support, an electrical insulating heat-conducting sheet on and conforming to said surface, and a shell on said sheet and conformingto said surface.

8. An electrical resistanceunit comprising electrical resistance, arranged to form an irregular surface, an electrical insulating sheet disposed on and conformed to the irregularities of the surface and an externally smooth metal sheet conformed to and in tight contact with the irregular external surface of the insulating sheet.

9. An electrical heater comprising a core, electrical resista-nce disposed about the core and forming thereon a surface having projections, non-combustible heat-conducting electrical insulation on said resistance and conforming` to the surface thereof over and y between the projections and a metal shell 1,-052, ses

sistance surface and in tight thermal contact therewith through the electrical insulation.

10. An electrical resistance device, eomprising a cylindrical insulated resistance element, and a cylindrical metallic shell in closs contact therewith under compression.

11. An electricalresistance device comprising electrical resistance arranged to form an irregular surface, an electrical insulating sheet disposed on and conformed to the irregularities 'of the surface, and an externally smooth metallic sheet conformed to and in tight contact with the irregular ort a s lit pin of low resistant conducting 5 b material extending through the support and having its head on the Side thereof with the resistance, said pin and said resistance being in electrical Contact. and a lead looped around the pin on the other side of the support, the limbs of said pin being bent. apart and toward the support and against said lead.

14. An electrical immersion heater comprising a resistance ou a core, insulation around the resistance; a. shell around the insulation a ca )art of which is inserted 7 v f beneath the shell and a packing of heat resisting water proof material at the joint between the shel and cap making said joint Water proof.

l5. An electrical innnersion;heater comprising a core, a shell around the core, a cap a part of which inserted betweenl the shell and the core, and a packing of heat resisting water proof material around the core between 'the core and the shell and between the shell and the cap.

lo. ln cfmibnation with an insulated electrical resistance ehement7 a casing therefor consisting ofv metal surrounding the resistance element and in a state of tension whereby it is caused to closely hug the resistance clement.

1T. In combination -with an insulated electrical resistance element, a shell therefor consisting of metal surrounding the resistance element and in a state of constrict ing` tension.

1S. An electrical heater comprising a support, leads extending. inside the support, electrical resistance disposed on the exterior of the sum'nrt, low resistant electrical conducting pieces between the leads and the terminals of the resistance, and a shell sur* rounding and electrically insulated from and in thermal Contact With the resistance.

I9. An electrical immersion heater, oomprising a resistance element, insulation over the resistance element, a sliell over the insun lation,l a cap joined to one edge of the shell, I and a packing of heat-resisting Water-proof i material at the joined portions of the shell 1o and the cap.

'In testimony whereof, I have hereunto set my hand at Los Angeles, California, this 21st day of April, 1910.

EDWARD J. OVINGTON.

In presence oit- JAMES R. TOWNSEND,

BELLE Riom. 

